getter-only-remote-data.js

class FetchTask {
  @tracked isLoading = true;
  @tracked result;

  constructor(url) {
    this.run(url);
  }

  async run(url) {
    let response = await fetch(url);
    this.result = await response.json();
    this.isLoading = false;
  }
}

class RemoteData {
  currentUrl = null;
  currentFetch = null;

  get(url) {
    if (url !== this.currentUrl) {
      this.currentFetch = new FetchTask(url);
      this.currentUrl = url;
    }

    return this.currentFetch;
  }
}

class MyComponent extends Component {
  remoteData = new RemoteData();

  get data() {
    return this.remoteData.get(this.args.url);
  }
}